Process of preparing chlorinated cycloolefin



United States Patent 3,326,842 PROCESS OF PREPARING CHLGRINATED CYCLOOLEFIN Arthur D. Ketley, Bethesda, Md., assignor to W. R. Grace & C0., New York, N.Y., a corporation of Connecticut No Drawing. Filed Apr. 2, 1964, Ser. No. 356,961 8 Claims. (Cl. 26033.8)

This invention relates to a method of preparing 4,4- dichloro-l-cyclopentene from 1,1-dichloro-2 vinylcyclopropane.

The article, Pyrolysis of 1,1-dichloro-2 vinylcyclopropane, Neureiter, Norman P., Journal of Organic Chemistry, 24, 2044 (1959), teaches the vacuum pyrolysis of 1,1-dichloro-2-vinylcyclopropane using an open, empty, i.e., unpacked, reaction tube. The article discloses that below 300 C. there was no conversion of 1,1-dich1oro-2- vinylcyclopropane and that at 325 C, there was only a 0.5% conversion. The article further discloses that at 375 C. there was a 12% conversion which contained 4,4- dichloro-l-cyclopentene in an amount of and that in the normal pyrolysis range of 475 to 525 C., a typical product contained 15 to of 4,4-dichloro-1-cyclopentene.

The disadvantages of producing 4,4-dichloro-l-cyclopentene according to the pyrolysis reaction set forth in the article are the high reaction temperatures and low yields.

It is a principal object of the instant invention to overcome the aforementioned disadvantages.

Briefly stated, the present invention comprises heating a substantially inert pyrolysis reaction zone packed with substantially indifferent material to a temperature in the range of 250 to 300 C., passing 1,1-dichloro-Z-vinylcyclopropane in vapor form through said reaction zone for a period of time sufficoent to form a vapor conttaining 4,4- dichloro-l cyclopentene and condensing the resulting vapor.

The thermal rearrangement of 1,1-dichloro-2-vinylcyclopropane to 4,4-dichloro-l-cyclopentene may be illustrated in equation form as follows:

1,1-dichloro-2-vinylcyclopropane may be prepared by the reaction of 1,3-butadiene, chloroform and potassiumt-butoxide. The reaction of the potassium-t-butoxide on the chloroform generates dichlorocarbene having the formula: CCl which reacts with the 1,3-butadiene to form 1,1dichloro-2-vinylcyclopropane.

The pyrolysis of 1,l-dichloro-2-vinylcyclopropane in the instant process should be carried out in a substantially inert zone, i.e., under anhydrous conditions in the absence of air, to avoid side reactions. Any conventional method may be used to provide the desired inert conditions. Usually an atmosphere of a substantially dry inert gas, such as nitrogen or argon, in the pyrolysis zone provides satisfactory inert conditions.

The temperature of the pyrolysis reaction may range from 250 to 300 C. Generally, temperatures lower than 250 C. will not convert the l,1-dichloro-2-vinylcyclopropane to 4,4'-dichloro-l-cyclopentene in significant amounts. On the other hand, temperatures higher than 300 C. ordinarily will cause the 4,4-dichloro-l-cyclopentene to dehydrochlorinate to give monochlorocyclopentadiene.

The pressure of the pyrolysis reaction may range from 3 ,326,842 Patented June 20, 1967 0.1 to 10 atmospheres. Atmospheric pressure, however, is preferred.

In the process of the present invention, the 1,1-dichloro-2-vinylcyclopropane is conducted through a heated pyrolysis reaction zone. For example, the compound may be passed through a pyrolysis reaction tube provided with equipment for heating. The reaction tube may be of porcelain, glass or quartz. Heat may be applied to the tube by a gas-fired furnace, an electric furnace, or by a simple winding of the tube with electrically heated resistance wire. The temperature of the tube may be recorded by manual or automatic devices, A protected thermo couple may be placed within the reaction tube if the tube is big enough.

The pyrolysis reaction zone should be packed with a substantially indifferent, i.e., inert, material of high surface area. The packing must be substantially inert so that it will not catalyze the pyrolysis reaction to produce products other than the desired 4,4-dichloro-l-cyclopentene. In addition, the packing must have high surface area so that substantially all of the vapor passed through the packed reaction zone is contacted with a surface heated to a pyrolyzing temperature. As a result, the 4,4-dichlorol-cyclopentene vapor is subjected to pyrolizing temperature uniformly.

Representative of the substantially inert materials suitable for use as packing in the pyrolsis reaction zone are glass fibers such as glass wool, glass particles such as glass helices and porcelain particles such as porcelain saddles.

The amount of 4,4-dichloro-l-cyclopentene produced according to the instant invention, will depend largely on the specific temperature of the pyrolysis reaction and the residence time of 1,l-dichloro-2-vinylcyclopropane in the pyrolysis reaction zone. Generally, with a residence time of /2 to 2 hours in the reaction zone at atmospheric pressure, the amount of 4,4-dichloro-l-cyclopentene produced in the temperature range of 250 C. to 300 C. will be about 30 to percent by weight of the starting material.

4,4-dichloro-l-cyclopentene is suitable as a plasticizer for polymers in general and especially such inflexible polymers :as poly-4-methylpentene-l, poly-3-methylbutene-1, and poly-4,4 dimethy1pentene-l. As a plasticizer, the 4,4- dichloro-l-cyclopentene may be used in amounts ranging from about .5 to 15 percent by weight of the polymer.

11 parts and percentages used herein are by weight unless otherwise indicated.

This invention is further illustrated by the following examples.

Unless otherwise stated, tests in the following examples were made as follows:

Gas chromatograms were prepared on a Perkin-Elmer Vapor Fractometer, Model 154, having a Perkin-Elmer K column and R column in series at 125 C.

The structure of the 4,4-dichloro-l-cyclopentene compound produced by pyrolysis was verified by nuclear magnetic resonance spectroscopy. The compound was dis sovled in carbon tetrachloride to form a solution equivalent to 15 parts by weight of the compound in cc. of carbon tetrachloride. The solution was then analyzed on a Varian HR 60 Nuclear Magnetic Resonance Spectrometer using tetramethylsilane as an internal reference.

Example 1 In this example, 1,1-dichloro-2-vinylcyclopropane was prepared.

A one liter four-necked reaction flask equipped with stirrer, dropping funnel, thermometer and condensor was used.

A flow of substantially dry argon was introduced into the flask and maintained throughout the reaction to provide anhydrous conditions.

The flask was flamed out under the argon and allowed to cool to room temperature. It was then immersed in a bath comprised of partially frozen carbon tetrachloride having a temperature of about -23 C.

239 grams (385 ml.) of 1,3-butadiene which had been dried by passing it through a column of anhydrous calcium sulfate (Drierite) and a column of anhydrous silica gel, was precooled to C. and added to the cooled reaction flask.

160 grams (1.6 moles) of potassium t-butoxide were then slowly added to the reaction flask with vigorous stirring.

170 grams (115 ml.) of chloroform, precooled to 20 C., were then added to the reaction flask with vigorous stirring.

About 100 ml. of n-pentane were then added to the reaction flask with vigorous stirring to disperse the potassium chloride solid which had formed and appeared to be agglomerating.

The reaction was allowed to continue with stirring at 23 C. for about 1 hour. At the end of this time, the reaction was stopped by pouring into dilute hydrochloric acid. The resulting organic layer was separated, washed with distilled water, separated again, and dried over anhydrous magnesium sulfate for 1 hour.

164 grams of 1,1-dichloro-2-vinylcyclopropane were obtained. This compound had a boiling point of 125 C. at 748 mm.

Example 2 In this example, 1,1-dichloro-2-vinylcyclopropane was thermally rearranged to 4,4-dichloro-l-cyclopentene.

A glass (Pyrex) pyrolysis reaction tube, 24 inches in length and 27 mm. in diameter, was packed tightly with glass wool. A thermocouple, encased in a glass capillary tube, was placed in the center of the pyrolysis reaction tube along a substantial length of the tube.

The reaction tube was placed in a vertical position and dry nitrogen was introduced into the top of the tube at a rate of about 15 to 20 ml. per minute. The reaction tube was wrapped with heating tape, the temperature of which was regulated by a powerstat. The top portion of the tube was provided with a dropping funnel. The bottom portion of the tube was connected to a condensor which was provided with a receiving flask.

A control gas chromatorgram of the 1,1-dichloro-2- vinylcyclopropane was made to evaluate the extent of the pyrolysis reaction.

The pyrolysis tube was raised to a temperature of 300 C. 15 ml. of the 1,1-dichloro-2-vinylcycl0propane were :introduced into the top of the pyrolysis reaction tube at :a rate of 100 ml. per hour. The resulting condensate was passed back through the reaction tube 5 times. The final icondensate Was a slightly brown liquid.

A gas chromatogram was made of the final condensate :and compared to the control gas chromatogram. Areas under the peaks of the chromatograms were determined.

The comparison showed that the condensate was com prised of 42% of a compound believed to be 4,4-dichlorol-cyclopentene, 54% of unreacted 1,1-dichloro-2-vinyl cyclopropane and 4% of other materials.

The 4,4-dichloro-l-cyclopentene was separated from the condensate on a gas chromatograph, Aerograph Model A350B, which had a dual column with a packing comprised of 80% diatomaceous earth (Chromasorb) and 20% polyethylene glycol (Carbowax 4000) terminated with terephthalic acid and a programmed temperature ranging from 50 C. to 180 C. increasing at a rate of 6 per minute.

The structure of the 4,4-dichloro-l-cyclopentene compound was then verified by nuclear magnetic resonance spectroscopy. The NMR spectrum at 60 megacycles Example 3 1,1-dichloro-2-vinylcyclopropane was prepared substantially as described in Example 1.

The 1,l-dichloro-2-vinylcyclopropane was the rmally converted to 4,4-dichloro-l-cyclopentene using the apparatus described in Example 2.

The pyrolysis tube was raised to a temperature of 275 C. 25 ml. of the 1,1-dichloro-2-vinylcyclopropane were introduced into the top of the tube at a rate of ml. per hour. The resulting condensate was passed back through the reaction tube 8 times. The final condensate was a slightly brown liquid.

The composition of the final condensate was determined as described in Example 2. The gas chromatogram showed that the condensate was comprised of 38% of 4,4-dichloro-l-cyclopentene, 59% of unreacted 1,1-dichlor0-2-vinylcyclopropane and 3% of other material.

The 4,4-dichloro-1-cyclopentene was separated from the condensate on the gas chromatograph, Aerograph Model A350B, as described in Example 2. Its structure was further determined by nuclear magnetic resonance spectroscopy as described in Example 2. The NMR spectrum at 60 megacycles showed two kinds of hydrogens in the ratio of about 2 to 1 with bands centered at +38 and +14 parts per ten million from benzene.

The boiling point of the 4,4-dichloro-l-cyclopentene was 123 C. at 760 mm.

Example 4 The poly-4-methylpentene-1 used in this example had a weight average molecular weight of 270,000, and a softening point of 232 C. The weight average molecular weight of poly-4-methylpentene-1 was determined by measuring the viscosity of 0.1 gram of the polymer in 100 cc. decalin at C.

30 grams of the poly-4-methylpentene-l were placed in a platen press and pressed at 300 F. at a pressure of 10,000 p.s.i. for 2 minutes. The polymer did not coalesce to form a film.

30 grams of the poly-4-methylpentene-1 were placed in a platen press and pressed at 400 F. at a pressure of 10,000 p.s.i. for 2 minutes. The resulting film was stiff and inflexible.

Example 5 The poly-4-methylpentene-1 used in this example had the same properties as that described in Example 4.

1.5 grams of the poly-4-methylpentene-1 were mixed with 0.1 gram of 4,4-dichloro-l-cyclopentene prepared as described in Example 2. The mixture was placed in a platen press and pressed at 300 F. at 10,000 p.s.i. for 3 minutes. The resulting film was clear, very flexible and rubbery.

What is claimed is:

1. A process of preparing 4,4-dichloro-l-cyclopentene which comprises heating a substantially inert reaction zone packed with substantially indifferent material to a temperature in the range of 250 C. to 300 C., passing 1,1-dichloro-2-vinylcyclopropane in vapor form through said heated reaction zone for a period of time suflicient to form a vapor containing 4,4-dichloro-l-cyclopentene, and condensing the resulting vapor.

2. A process according to claim 1 wherein the temperature is 300 C.

3. A process according to claim 1 wherein the temperature is 275 C.

4. A process according to claim 1 wherein the indifferent material is selected from the group consisting of glass fibers, glass particles and porcelain particles.

5. A process according to claim 1 wherein the indiffer- 8. A film formed from the composition of claim 7. ent material is glass Wool.

6. A composition comprised of high molecular weight References Clted poly-4-methylpentene-l and 4,4-dich1oro-1-cyclopentene, UNITED STATES PATENTS said 4,4-dichloro-l-cyclopentene being used in an amount 5 2,904,599 9/1959 Kleimon et a1 f to 15 p rcent by weight of said p0ly-4-methy1pen- 2,951 7 9 9 0 Neureiter 2,981,756 4/1961 Neureiter 260648 7. A composition according to claim 6 wherein the 4,4- dichloro-l-cyclopentene is present in an amount of 15 MORRIS LIEBMAN Pnmmy Examine"- percent by weight of said poly-4-rnethylpentene-1. 10 J. H. DERRINGTON, Assistant Examiner. 

6. A COMPOSITION COMPRISED OF HIGH MOLECULAR WEIGHT POLY-4-METHYLPENTENE-1 AND 4,4-DICHLORO-1-CYCLOPENTENE, SAID 4, 4-DICHLORO-1-CYCLOPENTENE BEING USED IN AN AMOUNT OF 0.5 TO 15 PERCENT BY WEIGHT OF SAID POLY-4-METHYLPENTENE-1. 